Probing Hydrophobic Interactions Using Trajectories of

Apr 1, 2009 - tions in favor of minimizing the solvent-associated surface area by collapsing into a compact ... A prism-based illumina- tion setup was...
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Published on Web 04/01/2009

Probing Hydrophobic Interactions Using Trajectories of Amphiphilic Molecules at a Hydrophobic/Water Interface Andrei Honciuc and Daniel K. Schwartz* Department of Chemical and Biological Engineering, UniVersity of Colorado, Boulder, Colorado 80309 Received January 30, 2009; E-mail: [email protected]

Abstract: Individual molecules of fluorophore-labeled alkanoic acids with various chain lengths, BODIPY-(CH2)n-COOH (abbreviated as fl-Cn), were observed to adsorb and move at the methylated fused silica-water interface as a function of temperature using total internal reflection fluorescence microscopy. The statistical analysis of squared-displacement distributions indicated that the molecular trajectories were consistent with a diffusive model involving two intertwined modes. The slower mode, typically responsible for